Older women who experience panic attacks may have an increased risk of a heart attack or stroke and an increased risk of death in the next five years.

The study, published in the Archives of General Psychiatry, finds that women who had a full-blown panic attack during a six-month period were three times more likely to have a heart attack or stroke over the next five years.

Panic attacks are the sudden development of fear, anxiety or extreme discomfort, and may be accompanied by shortness of breath or chest pains, among other symptoms. They can occur at random or as part of an anxiety disorder, such as social anxiety disorder or phobias.

Dr. Jordan W. Smoller of Massachusetts General Hospital in Boston, led a group who studied 3,369 healthy postmenopausal women (age 51 to 83). When they entered the study between 1997 and 2000, the women filled out a questionnaire about the occurrence of panic attacks in the previous six months.

About 10 per cent of the group, or 330 women, reported a full panic attack during the previous six months.

The women were then followed for an average of 5.3 years to see whether they had a heart attack or stroke or died from any cause. Forty-one of the 3,243 women in the group had a heart attack or death from a heart problem. An additional 40 had strokes.

Among the group that had reported having a panic attack, about four per cent had a heart attack or stroke. That compares with two per cent of the women who reported no panic attacks but who had heart attacks or strokes.

Once the researchers adjusted for other health factors, they found the heart and stroke risk was three times greater among women who had panic attacks.

Previous research has found that panic attacks are more common in women than in men. Smoller speculates that a panic attack may trigger heart rhythm problems. Or, it's possible that stress hormones released during an attack may harm the heart.